CFD Online Logo CFD Online URL
Home > Forums > Visualization & Post-Processing Software > Tecplot

stress vector variable calculation

Register Blogs Members List Search Today's Posts Mark Forums Read

LinkBack Thread Tools Search this Thread Display Modes
Old   December 11, 2020, 06:59
Default stress vector variable calculation
New Member
Join Date: Dec 2017
Posts: 2
Rep Power: 0
SYL is on a distinguished road

I want to calculate the shear stress for my 3D flow in a channel in the streamwise direction. To do so I used the code below. I can obtain the shear stress for any given volume by integrating the calculated stress tensor.

However, I want to see the distribution of shear stress like any given variable i.e. the stress at each node. A couple of questions:

1) I've calculated tau for each node but i cannot find the variable for the normal vector. Would simply calculating, for example, {taux} x {Y Grid K Unit Normal} be appropriate for txy (t = stress vector)?

2) my fluid quantities are calculated in the cartesian x-direction but in curved channel areas I need them to be streamwise. I can adjust direction using the equation below, but i'm unsure how best to apply it to every node in a region.
Currently, my method is A) select region using pick & select tool, B) value blank to just show region, C) calculate variable using the above equation. It feels a bit clunky and i'm unsure of the results (at least until 1 is sorted). Is there a better method?

Equation for variable adjustment (t= stress vector):
t =ρ(tzx cosθ + txy sin⁡θ)

Code for calculating stress tensor:
{D} = {dUdX} + {dVdY} + {dWdZ}
{T11} = 0.00089 * (2 * {dUdX} - 2/3 * {D}) - {Pressure}
{T12} = 0.00089 * ({dVdX} + {dUdY})
{T13} = 0.00089 * ({dWdX} + {dUdZ})
{T22} = 0.00089 * (2 * {dVdY} - 2/3 * {D})-{Pressure}
{T23} = 0.00089 * ({dVdZ} + {dWdY})
{T33} = 0.00089 * (2 * {dWdZ} - 2/3 * {D}) - {Pressure}
{taux} = {T11} * {X Grid K Unit Normal} + {T12} *{Y Grid K Unit Normal} + {T13} * {Z Grid K Unit Normal}
{tauy} = {T12} * {X Grid K Unit Normal} + {T22} *{Y Grid K Unit Normal} + {T23} * {Z Grid K Unit Normal}
{tauz} = {T13} * {X Grid K Unit Normal} + {T23} *{Y Grid K Unit Normal} + {T33} * {Z Grid K Unit Normal}

Apologies if this has been asked previously - looked through the older posts and couldn't find anything.
SYL is offline   Reply With Quote


shear stress, tecplot, unit normal

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On

Similar Threads
Thread Thread Starter Forum Replies Last Post
Cannot achieve negative wall shear stress values in CFD Post (ANSYS) SAtkins CFX 3 August 3, 2016 14:27
Calculation of Wall Shear Stress Dave442 CFX 36 July 12, 2016 04:12
Reynolds stress calculation from k-epsilon model Sae woong Kil CFX 2 December 4, 2008 17:59
calculation of Reynolds stress Z Main CFD Forum 0 March 3, 2005 12:32
Warning 097- AB Siemens 6 November 15, 2004 04:41

All times are GMT -4. The time now is 23:41.